CharacterMovementComponent boosted upward when falling into acute-angle sloped corner

In UCharacterMovementComponent::TwoWallAdjust, characters can gain unintended upward velocity (slope boosting) when hitting corners with an acute angle (<=90 degrees) while in the Falling movement mode. This occurs because the safety check HandleSlopeBoosting is bypassed in the acute-angle code path.

Root Cause

When a character hits two walls in one frame, the logic in UMovementComponent::TwoWallAdjust branches based on the dot product of the two wall normals:

• Obtuse Angles (Dot Product > 0): Calls ComputeSlideVector. The UCharacterMovementComponent override then applies HandleSlopeBoosting, which correctly prevents upward launches.
• Acute Angles (Dot Product <= 0): The function uses a cross-product projection and skips ComputeSlideVector entirely. Consequently, HandleSlopeBoosting is never called, leaving the vertical velocity unchecked.

UCharacterMovementComponent overrides TwoWallAdjust but does not have additional logic for IsFalling() state.

1. Create a level with two walls meeting at a sharp angle (≤90°), at least one wall having a ramp/slope.
2. Make a Character fall into the corner while horizontal velocity is applied each frame (e.g. via SetVelocity).
3. Observe the character being pushed upward without bound.
4. With an obtuse-angle corner, no upward pushing occurs.

Check out the attached repro project and video